Hold the two lugs on the edge of the circle and strike a line down the straight edge.
Turn approx 45 degrees do same again you have found the center.
I have had this tool for years, it is part of late fathers collection, but i have not really took much notice of it until today, now i know it is a center finder but how does it work ...
Richard Kell just a few miles down the road from me at Choppington still makes a nice brass version
Richard Kell just a few miles down the road from me at Choppington still makes a nice brass version